[21a-PA1-1~15] 3.2 Equipment optics and materials

[21a-PA1-12] Focal Depth Extension Owing to Annular Pupil Phase Mask Derived from Iterative Phase Retrieval Algorithm

〇Katsuhiro Uno¹ (1.Ibaraki Univ.)

Keywords:iterative phase retrieval, pupil filter, focal depth

We designed a pupil phase filter that expands the depth of focus using the iterative phase retrieval method. We divided the pupil plane into plural concentric annular regions and assigned different focal lengths for each region. Then, we applied an iterative algorithm of phase estimation until a desired spot diameter is obtained at the focal plane for each region. Finally, by integrating these phase distributions and calculating the spot diameter around the focal plane for the Gaussian incident beam, a minute spot diameter was maintained over a wide range around the focal plane.